Comparison of estimates of ruminal protein degradation by in vitro and in situ methods

G A Broderick, R J Wallace, E R Orskov, L Hansen

Research output: Contribution to journalArticle

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Abstract

Ruminal degradation of eight soluble proteins and 10 protein meals was determined using three methods: 1) an inhibitor in vitro system (IIV), to which inhibitors are added to prevent metabolism of protein degradation products, 2) in situ incubations in nylon bags and 3) in vitro NH3 production in typical ruminal inoculum. In vitro NH3 production rate from different proteins was not related to in situ or IIV degradation rate. Degradation rates for soluble proteins by IIV ranged from .103 to .813/h, yielding estimated extents of degradation that ranged from 73 to 94% (assuming ruminal passage of .05/h). For seven of the protein meals, degradation rates measured by IIV were threefold greater than in situ rates. However, mean degraded fractions estimated from zero-time intercepts were twofold greater using the in situ method, and calculated extents of degradation averaged 83% of IIV values. Extents of degradation estimated (assuming ruminal passage of .05/h) for fish meal, soybean meal, linseed meal, sunflower meal, rapeseed meal, copra meal and meat and bone meal were, respectively; 55, 79, 84, 59, 75, 54 and 58% (IIV) and 46, 63, 69, 51, 52, 43 and 55% (in situ). These values were generally similar to those reported in the literature. The extent of degradation of feather meal was 28% by in situ determination. Neither the IIV nor in situ method gave significant regressions for blood meal; neither method yields reliable data for very slowly degraded proteins. The IIV procedure has the advantage over the in situ method because it can yield degradation estimates for soluble as well as insoluble proteins.
Original languageEnglish
Pages (from-to)1739-1745
Number of pages7
JournalJournal of Animal Science
Volume66
Issue number7
DOIs
Publication statusPublished - Jul 1988

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protein degradation
Proteolysis
Meals
degradation
proteins
methodology
Proteins
linseed meal
coconut meal
feather meal
sunflower meal
In Vitro Techniques
rapeseed meal
meat and bone meal
Flax
Feathers
Brassica rapa
blood meal
Helianthus
nylon

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Comparison of estimates of ruminal protein degradation by in vitro and in situ methods. / Broderick, G A; Wallace, R J; Orskov, E R; Hansen, L.

In: Journal of Animal Science, Vol. 66, No. 7, 07.1988, p. 1739-1745.

Research output: Contribution to journalArticle

Broderick, G A ; Wallace, R J ; Orskov, E R ; Hansen, L. / Comparison of estimates of ruminal protein degradation by in vitro and in situ methods. In: Journal of Animal Science. 1988 ; Vol. 66, No. 7. pp. 1739-1745.
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